Pharma giant Biogen has entered into a definitive agreement to acquire Apellis Pharmaceuticals, maker of geographic atrophy drug Syfovre, in a deal worth about $5.6 billion. Under the terms of the agreement, Biogen will acquire all outstanding shares of Apellis for $41 per share in cash. In addition, Apellis shareholders will receive a nontransferable contingent value right (CVR) per share, which could deliver up to $4 in additional payments tied to future sales milestones for Syfovre. The CVR structure provides additional upside for Apellis shareholders based on Syfovre's performance. Payments are tied to achieving annual global net sales thresholds of $1.5 billion and $2 billion between 2027 and 2030, with a potential fallback payment in 2031. The $41 per share offer represents an 86% premium to Apellis’ 90-day volume-weighted average price and a 35% premium to its 52-week high. The acquisition is expected to close in the second quarter of 2026, pending regulatory approvals and customary closing conditions. The deal brings two commercial-stage therapies—Syfovre and Empaveli—into Biogen’s portfolio. The drugs generated combined net sales of $689 million ($587 million from Syfovre) in 2025 and are projected to grow at a mid-to-high teens rate through at least 2028, according to Biogen. Syfovre (pegcetacoplan), a targeted C3 therapy, was approved by the FDA in February 2023, making it the first approved therapy in the United States for GA. Shortly after, in August 2023, Astellas' Izervay (avacincaptad pegol) was approved by the FDA for the treatment of GA. The approval of Syfovre was approved based on positive results from the phase 3 OAKS and DERBY studies at 24 months. In those studies, Syfovre demonstrated increasing effects over time, with the greatest benefit—up to 36% reduction in lesion growth with monthly treatment in the DERBY study—occurring between months 18 and 24. In November 2025, Apellis presented a post-hoc analysis of its 5-year long-term efficacy data from the GALE open-label extension study, showing Syfovre delayed GA lesion progression by approximately 1.5 years in patients with nonsubfoveal GA when compared to sham/projected sham. Syfovre is approved in the United States and Australia, although it's efforts to receive approval in Europe were unsuccessful. Meanwhile Empaveli (pegcetacoplan), also a complement C3 inhibitor, is approved for several rare kidney diseases—including C3 glomerulopathy (C3G) and primary IC-MPGN—as well as paroxysmal nocturnal hemoglobinuria (PNH). Biogen expects a "significant proportion" of Apellis's 740 employees to join the company. Biogen will continue to work with Sobi, which retains commercial rights to Empavli (Aspaveli in the EU) outside the U.S. “Consistent with our strategy, this acquisition immediately advances Biogen’s ongoing transformation. The addition of Apellis expands our growth portfolio in immunology and rare disease with two approved, best-in-class medicines that complement our existing portfolio and bolsters our near-and long-term growth potential,” said Christopher A. Viehbacher, Biogen’s President and CEO. “I am incredibly proud of the Apellis team and what we have achieved, including bringing two transformational medicines–Syfovre and Empavli – to patients and building an innovative pipeline leveraging our deep expertise in complement science,” said Cedric Francois, MD, PhD, co-founder and CEO of Apellis. “With Biogen’s extensive experience with immunology and rare disease, we believe this transaction will accelerate our impact and enable us to reach more patients. This transaction represents a compelling outcome for our shareholders and a strong validation of our strategy, scientific innovation, and execution.”